1. Field of the Invention
The present invention relates to connectors for high-speed signal transmission. More specifically, the present invention relates to connectors in which wires are directly connected to contacts of the connectors.
2. Description of the Related Art
High-speed cable routing has been used to transmit signals between substrates, such as printed circuit boards, of electronic devices. Conventional high-speed cable routing often requires routing in very tight and/or low-profile spaces. However, as data rates increase (i.e., the frequency of the high-speed signal increases), the cost of high-performance high-speed transmission systems increases as well. High-speed signals transmitted from between substrates generally follow a path of:                1) a trace of the transmitting substrate;        2) a first connector mounted to the transmitting substrate;        3) a substrate of a second connector that is inserted into the first connector;        4) a high-speed cable connected to the second-connector substrate at a transmitting end of the high-speed cable;        5) a substrate of a third connector connected the high-speed cable at a receiving end of the high-speed cable;        6) a fourth connector, mounted to the receiving substrate, that receives the third-connector substrate; and        7) a trace of the receiving substrate.        
Conventional high-speed cable assemblies typically include two connectors (i.e., the second and third connectors listed above) that are connected by high-speed cables. Accordingly, conventional high-speed cable routing also requires an additional two connectors (i.e., the first and fourth connectors listed above) to connect the high-speed cables to transmitting and receiving substrates.
The signal quality is affected every time the transmitted signal transfers from each of the listed items above. That is, the signal quality is degraded when the signal is transmitted between 1) the trace of the transmitting substrate and 2) the first connector mounted to the transmitting substrate, between 2) the first connector mounted to the transmitting substrate and 3) the second-connector substrate that is inserted into the first connector, etc. The signal quality can even be affected within each of the items above. For example, a signal transmitted on the trace of the transmitting or receiving substrate can suffer significant insertion loss.
High-speed cable assemblies are relatively expensive, due in part to the cost of high-speed cable and the two connectors that include substrates (i.e., the second and third connectors listed above). Each connector of the high-speed cable assembly also requires processing time. Thus, the full cost of a high-speed cable assembly cable includes the cable, the high-speed-cable-assembly connectors on each end of the cable, the processing time required for each of these connectors, and the area required on a substrate for each connector.
To reduce the overall size of the high-speed cable assembly, smaller connectors and cables have been attempted. However, using smaller connectors and cables can both increase the cost and reduce the performance of high-speed cable assemblies. Eliminating the high-speed cable assembly has been attempted by transmitting the signal only on substrates. However, signals transmitted on a substrate generally have higher insertion losses compared to many cables, including, for example, micro coaxial (coax) and twinaxial (twinax) cables. Thus, eliminating the high-speed cable assembly can result in reduced signal integrity and degraded performance.
Exotic materials and RF/Microwave connectors have been used to improve the performance of high-speed cable assemblies. However, such materials and connectors increase both the cost and the size of a high-speed cable assembly. Low-cost conductors, dielectrics, and connectors have been used to reduce the overall cost of systems that rely on high-speed cable routing. However, low-cost conductors, dielectrics, and connectors decrease the performance of high-speed cable assemblies and can also increase their size.